[amsat-bb] FM signal on FO-29?
zleffke at vt.edu
Sun Nov 8 23:40:48 UTC 2015
That makes sense Hector. I've seen the FM activity kind of all over the
transponder. More so than I would expect if it was the same transmitter
each time on the same frequency and the different pass geometries
causing a bit of swing due to doppler.
On 11/08/2015 06:34 PM, Hector W5CBF/CO6CBF wrote:
> Hi Zach and group
> I think, the main problem is they are not always the same stations. I have
> heard several different stations in terrestrial QSOs QRMing FO-29; majority
> of them speaking Spanish and without any kind of ID. I have not heard them
> recently, though.
> Hector, CO6CBF/W5CBF
> -----Mensaje original-----
> De: AMSAT-BB [mailto:amsat-bb-bounces at amsat.org] En nombre de Zach Leffke
> Enviado el: Sunday, November 08, 2015 4:54 PM
> Para: amsat-bb at amsat.org
> Asunto: Re: [amsat-bb] FM signal on FO-29?
> well.. when I say students, I meant graduate students at VT that happened to
> be in the lab when I was doing the experiment. They work with me and Bob,
> so a few crude words here and there aren't uncommon to them.
> But good point, probably not the best thing for a public demo if your
> audience is a bit younger.
> Actually, I've seen so much FM activity (basically every time I've monitored
> FO-29 since we first came online in late september) that I've been toying
> with the idea of trying to locate where the source emitters actually are
> located based on doppler shift data. We know the doppler between the
> receiving ground station and FO-29, so we can back that out. We know the
> transponder mapping, so we can work through that to determine what the
> center frequency is as the signal enters the transponder uplink receiver.
> What we don't know is the uplink doppler, because we don't know where the
> emitter is and we don't know what exact center frequency they are on (but I
> bet you its in 5kHz steps, maybe 2.5kHz). So we have two unknowns. I'm
> betting there's a way to work through it though, and with enough
> observations and by watching the rate of change of the doppler, I bet
> there's a way to make an educated guess on what their center freq and
> location are.
> Or if someone listening knows Spanish and/or Portugese, maybe we could get
> lucky and hear what cross streets the taxi is going to (if it is in fact a
> -Zach, KJ4QLP
> On 11/08/2015 05:30 PM, Clayton W5PFG wrote:
>> I wouldn't recommend playing the FM audio heard via FO-29 to a group
>> of children. Normally it's not English. It's most likely NOT a
>> religious broadcast based on their choice of crude words.
>> On 11/8/2015 16:13, Zach Leffke wrote:
>>> So yes, in the last couple weeks I've seen a LOT of FM activity on
>>> FO-29. And based on my experience with Friday's pass, which was
>>> ascending, I'm leading towards the Central/South America QRM theory.
>>> Lots of strong FM activity as the pass started and the satellite was
>>> over the lower latitudes, but as FO-29 ascended over higher latitudes
>>> towards the north pole, the FM activity died down.
>>> -Zach, KJ4QLP
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